import beamcoder from 'beamcoder';
import path from 'path';
import { performance } from 'perf_hooks';

export async function run() {
  const startTime = performance.now();
  const demuxer = await beamcoder.demuxer(
    `file:${path.resolve('example.wav')}`
  );
  const decoder = await beamcoder.decoder({
    params: demuxer.streams[0].codecpar
  });
  const encoder = await beamcoder.encoder({
    name: 'libopus',
    time_base: demuxer.streams[0].time_base,
    sample_fmt: 's16',
    sample_rate: 24000,
    channels: 1,
    bit_rate: 64000,
    channel_layout: 'mono'
  });
  const filterer = await beamcoder.filterer({
    filterType: 'audio',
    // FIXME: Should we use p=0 or p=1?
    // If set to 1, the filter will pad the last audio frame with zeroes,
    // so that the last frame will contain the same number of samples as the previous ones.
    // Default value is 1
    filterSpec: `asetnsamples=n=${(encoder.sample_rate / 1000) * 20}:p=1`,
    inputParams: [
      {
        channelLayout: decoder.channel_layout,
        sampleFormat: decoder.sample_fmt,
        sampleRate: decoder.sample_rate,
        timeBase: decoder.time_base
      }
    ],
    outputParams: [
      {
        channelLayout: encoder.channel_layout,
        sampleFormat: encoder.sample_fmt,
        sampleRate: encoder.sample_rate
      }
    ]
  });
  const muxer = beamcoder.muxer({ filename: 'file:result.ogg' });

  const stream = muxer.newStream({
    name: 'libopus',
    extradata: Buffer.from('T3B1c0hlYWQBATgBwF0AAAAAAA==', 'base64'),
    sample_rate: encoder.sample_rate,
    sample_fmt: encoder.sample_fmt,
    channels: demuxer.streams[0].codecpar.channels,
    time_base: demuxer.streams[0].time_base
  });
  Object.assign(stream.codecpar, {
    extradata: Buffer.from('T3B1c0hlYWQBATgBwF0AAAAAAA==', 'base64'),
    sample_rate: encoder.sample_rate,
    sample_fmt: encoder.sample_fmt,
    channels: demuxer.streams[0].codecpar.channels,
    time_base: demuxer.streams[0].time_base
  });

  await muxer.openIO();
  await muxer.writeHeader();

  while (true) {
    const packet = await demuxer.read();
    if (!packet) break;

    const packets = await decoder
      .decode(packet)
      .then((result) => filterer.filter(result.frames))
      .then((result) => result[0].frames)
      .then((frames) => encoder.encode(frames))
      .then((result) => result.packets);

    for (const packet of packets) await muxer.writeFrame(packet);
  }
  await muxer.writeTrailer();
  console.log(`Took ${(performance.now() - startTime).toFixed(1)}ms`);
  global.gc()
}

run();